1. Field of the Invention
The present invention relates to a method and apparatus for forming and recording a composite image resulting from a magnetic latent image and an electrostatic latent image.
2. Description of the Prior Art
Xerography is a process which is well known in the art from the disclosure made in U.S. Pat. No. 2,297,691 granted to Carlson. This process is an electrophotography process according to which an electrostatic latent image is formed on a photosensitive medium and then the latent image is developed to produce a copied image. The photosensitive medium used in the process is composed of an electrically conductive substrate and a photoconductive layer provided on the substrate.
As a development of the above electrophotographic process, it is also known to reproduce an image employing a photosensitive medium of three-layer structure which further comprises a transparent insulating layer laid on the above mentioned photoconductive layer. This process is generally called NP process and is disclosed, for example, in U.S. Pat. No. 3,666,363.
Another type of image forming process is disclosed in U. S. Pat. No. 3,250,636 and Japanese Patent Application laid open No. 90,342/1975. This process comprises the steps of forming a magnetic latent image on a magnetic drum using a magnetic recording head, developing the formed latent image with a magnetic toner and transferring the developed image onto a recording paper.
Various methods and apparatus have been proposed in order to compound two different images into a composite image and to record the composite image using the principle of xerography. However, the manner of forming a composite image is common to all of these methods hitherto proposed. Namely, the different electrostatic latent images are compounded to form a composite image on a recording medium, and the composite image is then visualized. Since both of the latent images are electrostatic latent images, selective writing or erasing of any particular part of image information may be realized only with great difficulty and inconvenience. Such realization necessitates use of a very complicated process. The apparatus required to carry out the process becomes unduly expensive, complicated in structure, and large in size.